Multilayer planar or tubular fooodstuff wrapping or film

ABSTRACT

Multilayer planar or tubular food casing or film The present invention for the first time furnishes a multilayer planar or tubular food casing or film for food packagings such as, e.g., sausage casings, shrink bags or the like, which comprises a layered structure having at least five, preferably at least seven layers.

The present invention relates to a multilayer planar or tubular foodcasing or film for food packagings such as, e.g., sausage casings,shrink bags or the like, in accordance with the preamble of Claim 1.

DE 32 12 343 A1 discloses a tubular casing of two-layer film laminatefor packaging.

Furthermore a multilayer, tubular casing for packaging pasty stuffings,in particular an artificial sausage casing, on the basis of polyamide isdiscussed in DE 40 17 046 A1 as well as in EP 0 467 039 A2.

In practice, such sausage casings or artificial casings are utilized forpackaging sausage or pasty matter. The product to be packaged, such as asausage mass, is filled into the artificial casing, scalded in it,cooled, and stored. From this there arise demands such as, e.g., adistinct dimensional stability throughout the entire working process ora sufficient protection of the stuffing against external influences suchas, e.g., penetration of oxygen, UV radiation, desiccation, or the like.

The classical sausage casings known in practice may roughly beclassified into three types: The classical one-layer sausage casing ofpolyamide, having as an essential drawback the lack of a water vaporbarrier. A widely used sausage casing of three layers containing, fromthe outside to the inside, polyamide, polyolefin, preferablypolyethylene, polyamide. The water vapor barrier, which is lacking inthe one-layer sausage casing, is formed by the central polyolefin layer.The inner layer of polyamide provides sufficient adhesion of stuffingand prevents precipitation or settling of jelly. This polyamide layermay also be replaced with a correspondingly pre-treated (corona) PElayer, in which case the PE layer then has to be modified in order toenter a satisfactory connection with the PA. In recent times, sausagecasings having five layers have found acceptance in practice. The fivelayers, counted from the outside to the inside, contain PA, an adhesionpromoter, PE, an adhesion promoter, and finally again PA. The approachof this structure corresponds to the one of the three-layer sausagecasing, however has between PA and PE, and between PE and PA, arespective separate adhesive layer or a respective separate adhesionpromoter. As a result the central polyolefin layer may be modified morestrongly with regard to the starting materials used.

Irrespective of this, the oxygen barrier and also the aroma barrierthereby available are not yet formed with sufficient tightness.

It is accordingly an object of the present invention to further developa generic multilayer planar or tubular food casing or film whileavoiding the above mentioned disadvantages, such that a sufficientlytight oxygen barrier may be furnished concurrently with a satisfactoryaroma barrier.

This object is achieved through the features of Claim 1.

In accordance with the invention a multilayer planar or tubular foodcasing or film for food packagings, such as, e.g., sausage casings,shrink bags etc., is being proposed, which is for the first timecharacterized by a layered structure having at least five, preferably atleast seven layers, with one of the at least five layers containing PVAas a layer constituent.

For particularly preferred variants of the multilayer planar or tubularfood casing or film for food packagings in accordance with theinvention, the following layered structures, counted from the outside tothe inside, are being proposed for the first time:

a) the first layer from the outside contains polyamide as a layerconstituent, the second layer PVA, the third layer an adhesion promoter,the fourth layer a polyolefin, preferably polyethylene, the fifth layeran adhesion promoter, and the sixth layer from the outside, being at thesame time the innermost layer or the layer facing the food to bepackaged, a polyamide as a layer constituent, ‘or b) the first layerfrom the outside contains polyamide as a layer constituent, the secondlayer PVA, the third layer polyamide, the fourth layer an adhesionpromoter, the fifth layer a polyolefin, preferably polyethylene, thesixth layer an adhesion promoter, and the seventh layer from theoutside, being at the same time the innermost layer or the layer facingthe food to be packaged, a polyamide as a layer constituent,

or c) the first layer from the outside contains polyamide as a layerconstituent, the second layer an adhesion promoter, the third layerpolyamide, the fourth layer PVA, the fifth layer polyamide, the sixthlayer an adhesion promoter, and the seventh layer from the outside,being at the same time the innermost layer or the layer facing the foodto be packaged, a polyamide as a layer constituent.

Furthermore particularly preferred variants of a multilayer planar ortubular food casing or film for food packagings in accordance with theinvention are for the first time proposed which have a layered structurewherein, when counted from the outside to the inside:

a) the first layer from the outside contains as a layer constituent apolyolefin, preferably polyethylene, the second layer an adhesionpromoter, the third layer polyamide, the fourth layer PVA, the fifthlayer polyamide, the sixth layer an adhesion promoter, and the seventhlayer from the outside, being at the same time the innermost layer, apolyolefin, preferably polyethylene,

or b) the first layer from the outside contains as a layer constituentPET, the second layer an adhesion promoter, the third layer polyamide,the fourth layer PVA, the fifth layer polyamide, the sixth layer anadhesion promoter, and the seventh layer from the outside, being at thesame time the innermost layer, a polyolefin, preferably polyethylene,

or c) the first layer from the outside contains as a layer constituent apolyolefin, preferably polyethylene, the second layer EVA, the thirdlayer an adhesion promoter, the fourth layer PVA, the fifth layer anadhesion promoter, the sixth layer EVA, and the seventh layer from theoutside, being at the same time the innermost layer, a polyolefin,preferably polyethylene.

PVA advantageously results in the desired high oxygen barrier, with asimultaneously substantially enhanced aroma barrier. Furthermore asmoother and softer film is thereby achieved, which is substantiallyimproved with a view to its suitability for further mechanicalprocessing. PVA in this context designates polyvinyl alcohol which mayalso be abbreviated PVOH or PVAL. PVA is to designate both PVA andmixtures of PVA with other polymers.

The PA allows to ensure the desired mechanical properties. The PEprovides the possibility of positively influencing sealing. With EVA,high shrink as well as a further possibility of influencing themechanical properties are moreover obtained, in which case asupplementary electron beam treatment is to be provided.

The polyolefins encompass both PE and PP as well as EVA and EM(M)Awithin the meaning of the present application, as well as mixtures ofpolyolefins as such as well as with ionomers. The adhesion promoters(short: AP) represent an adhesive layer.

PA generally designates PA as well as PA 6, PA 66, PA 6/66, PA 6/12 orthe like, and also mixtures of these, as well as mixtures of PA withother polymers. EVA furthermore designates both EVA and mixtures of EVAwith polymers.

Thus a food casing or film for food packagings, in particular forsausage casings or the like is advantageously furnished, whereby aspecific shrink of at least 10 to 20%, preferably of at least 12 to 15%,is readily possible.

Specifically in the case of shrink bags or the like, it isadvantageously possible with the layered structures proposed for thefirst time, to achieve a particularly high shrink that is at least 20 to60%, preferably at least 30 to 50%, at a water temperature of about 95°C.

The overelongation factor thus available at the same time is at least 5to 15%, preferably 10 to 12% for both sausage casings and shrink bags.

For the sealing layers to be provided on the inside and/or outside ofshrink bags, it is possible with the layered structures proposed for thefirst time to advantageously provide, e.g., a polyolefin, preferably PE,LLDPE, EVA, or ionomers or mixtures of these etc., as a startingmaterial.

Thanks to the particularly strongly pronounced oxygen barrier obtainedthrough the layer constituent PVA, excellent preservation of thefoodstuff thereby packaged, in particular of a sausage mass placed inthe sausage casing, is ensured over more than six weeks without anyquality reduction.

Thanks to the extremely well formed oxygen barrier, the food casing orfilm of the invention for the first time provides a food packagingwhereby even goods that are particularly sensitive to air do not undergoany color changes or even run a risk of aging or changing taste due to apenetration of oxygen, even with long storage periods.

Thus the layer constituent PVA is in a preferred layered structureembedded, in the manner of a sandwich, between two layers includingpolyamide as a layer constituent, which results in a highest possibleoxygen barrier and at the same time ensures excellent embedding andstabilization of the PVA layer between the two polyamide layers ascarrier layers.

At the same time a particularly excellent water vapor barrier isavailable with the layered structure of the invention, which is crucialparticularly in the case of sausage or other foodstuffs that need to bekept fresh. Foods packaged with the food casing or film of the inventiontherefore remain fresh for a particularly long period of time.

Furthermore the food casing or film of the invention is suited as ashrink film and may moreover be sealed well during bonding. Where thefood casing or film of the invention is used as a sausage casing, purebonding is equally possible without any problems.

The outermost layer of the food casing or film proposed for the firsttime takes inscriptions or print particularly well.

In addition, the food casing or film of the invention is particularlywell suited to be manufactured and further processed with correspondingsystems of the present applicant.

Advantageous developments of the invention result from the features ofthe subclaims.

Thus it is provided in a preferred embodiment of the food casing or filmfor food packagings in accordance with the invention that layersincluding polypropylene or polyolefin as a layer constituentalternatively also contain polypropylene, EVA (ethyl vinyl alcohol),EM(M)A, ionomers, or mixtures of these etc.

Furthermore it is provided in a preferred embodiment that layerscontaining an adhesion promoter include an adhesion promoter on thebasis of PE, EVA, EM(M)A or an ionomer as a base material.

In accordance with a further preferred embodiment it is provided thatlayers including an adhesion promoter as a constituent alternativelycontain a mixture of polyolefin and adhesion promoter or a mixture ofEVA and/or EM(M)A and adhesion promoter.

In accordance with a further preferred embodiment it is provided thatlayers including PVA as a layer constituent alternatively contain MXD6(modified polyamide 6).

In accordance with a further preferred embodiment of the food casing orfilm of the invention it is provided that layers including polyamide asa layer constituent alternatively contain an ionomer.

Furthermore it is provided in accordance with a preferred embodimentthat layers including polyamide as a layer constituent alternativelycontain MXD6.

Not last it is provided in accordance with a preferred embodiment thatlayers including polyamide as a layer constituent containpolycaprolactame (PA 6), polyhexamethylene adipinamide (PA 66), PA 6/66,PA 11, PA 12 or mixtures of these polyamides etc.

By the present invention a planar or tubular food casing or film havinga layered structure with at least five layers, preferably at least sevenlayers, is thus proposed for the first time.

1-10. (canceled)
 11. Multilayer planar or tubular food casing or filmfor food packagings such as, e.g., sausage casings, shrink bags etc.,characterized by a layered structure having at least five, preferably atleast seven layers, with one of the at least five layers containing PVAas a layer constituent, and wherein the layer containing PVA is embeddedbetween two layers containing polyamide as a layer constituent. 12.Multilayer tubular food casing or film for sausage casings,characterized by a layered structure having at least five, preferably atleast seven layers, with one of the at least five layers containing PVAas a layer constituent, and having the following layered structure whencounted from the outside to the inside: a) the first layer from theoutside contains polyamide as a layer constituent, the second layer fromthe outside contains PVA as a layer constituent, the third layer fromthe outside contains an adhesion promoter as a layer constituent, thefourth layer from the outside contains a polyolefin, preferablypolyethylene, as a layer constituent, the fifth layer from the outsidecontains an adhesion promoter as a layer constituent, and the sixthlayer from the outside contains polyamide as a layer constituent, or b)the first layer from the outside contains polyamide as a layerconstituent, the second layer from the outside contains PVA as a layerconstituent, the third layer from the outside contains polyamide as alayer constituent, the fourth layer from the outside contains anadhesion promoter as a layer constituent, the fifth layer from theoutside contains a polyolefin, preferably polyethylene, as a layerconstituent, the sixth layer from the outside contains an adhesionpromoter as a layer constituent, and the seventh layer from the outsidecontains polyamide as a layer constituent, or c) the first layer fromthe outside contains polyamide as a layer constituent, the second layerfrom the outside contains an adhesion promoter as a layer constituent,the third layer from the outside contains polyamide as a layerconstituent, the fourth layer from the outside contains PVA as a layerconstituent, the fifth layer from the outside contains polyamide as alayer constituent, the sixth layer from the outside contains an adhesionpromoter as a layer constituent, and the seventh layer from the outsidecontains polyamide as a layer constituent.
 13. Multilayer planar ortubular food casing or film for shrink bags, characterized by a layeredstructure having at least five, preferably at least seven layers, withone of the at least five layers containing PVA as a layer constituent,and having the following layered structure when counted from the outsideto the inside: a) the first layer from the outside contains apolyolefin, preferably polyethylene, as a layer constituent, the secondlayer from the outside contains an adhesion promoter as a layerconstituent, the third layer from the outside contains polyamide as alayer constituent, the fourth layer from the outside contains PVA as alayer constituent, the fifth layer from the outside contains polyamideas a layer constituent, the sixth layer from the outside contains anadhesion promoter as a layer constituent, and the seventh layer from theoutside contains a polyolefin, preferably polyethylene, as a layerconstituent, or b) the first layer from the outside contains PET as alayer constituent, the second layer from the outside contains anadhesion promoter as a layer constituent, the third layer from theoutside contains polyamide as a layer constituent, the fourth layer fromthe outside contains PVA as a layer constituent, the fifth layer fromthe outside contains polyamide as a layer constituent, the sixth layerfrom the outside contains an adhesion promoter as a layer constituent,and the seventh layer from the outside contains a polyolefin, preferablypolyethylene, as a layer constituent, or c) the first layer from theoutside contains a polyolefin, preferably polyethylene, as a layerconstituent, the second layer from the outside contains EVA as a layerconstituent, the third layer from the outside contains an adhesionpromoter as a layer constituent, the fourth layer from the outsidecontains PVA as a layer constituent, the fifth layer from the outsidecontains an adhesion promoter as a layer constituent, the sixth layerfrom the outside contains EVA as a layer constituent, and the seventhlayer from the outside contains a polyolefin, preferably polyethylene,as a layer constituent.
 14. Food casing or film for food packagings inaccordance with claim 11, characterized in that layers containing apolyolefin, preferably polypropylene, as a layer constituentalternatively also contain additional polyolefins, polypropylene, EVA(ethyl vinyl alcohol), EM(M)A, ionomers, or mixtures of these, etc. 15.Food casing or film for food packagings in accordance with claim 11,characterized in that layers containing an adhesion promoter include anadhesion promoter based on PE, EVA, EM(M)A or an ionomer as a basematerial.
 16. Food casing or film for food packagings in accordance withclaim 1 1, characterized in that layers including an adhesion promoteras a constituent alternatively contain a mixture of polyolefin andadhesion promoter or a mixture of EVA and/or EM(M)A and adhesionpromoter.
 17. Food casing or film for food packagings in accordance withclaim 11, characterized in that layers including PVA as a layerconstituent alternatively contain MXD6 (modified polyamide 6).
 18. Foodcasing or film for food packagings in accordance with claim 11,characterized in that layers including polyamide as a layer constituentalternatively contain an ionomer.
 19. Food casing or film for foodpackagings in accordance with claim 11, characterized in that layersincluding polyamide as a layer constituent alternatively contain MXD6.20. Food casing or film for food packagings in accordance with claim 11,characterized in that layers including polyamide as a layer constituentcontain polycaprolactame (PA 6), polyhexamethylene adipinamide (PA 66),PA 6/66, PA 11, PA 12, or mixtures of these polyamides, etc.